Anna University
ELECTRICAL MACHINES – 1
Semester 4
Department of Electrical and Electronics Engineering
Important Part B Questions
Unit- 1
1. Explain AC operation of magnetic circuits and derive the energy stored in magnetic field .(8)*
2. Explain the core losses that occurs in magnetic circuits in detail. (8*)
3. Explain in detail how the emf is induced . (16)*
4. Compare magnetic circuits and electric circuits (8)*
5. Explain (a)leakage flux( b)stacking factor (c) air gap. (8)
Unit -2
1. Explain parallel operation of single phase transformer. And derive the emf equation of transformers. (16)*
2. Explain the working and construction of auto transformer in detail.(8)
3. Draw and explain the equivalent circuits of transformer (16)
4. Explain all the three phase transformer connections . (16)*
5. Explain a)transformer on ON load b)transformers on NO load conditions. (Each 8 )
Unit -3
1. Explain in detail singly excited magnetic system (be in knowledge with full derivation in safer side ) .(16)*
2. Explain in detail multiply (or) doubly excited magnetic system .(16)*
3. Draw and explain the energy flow diagram for a motor and generator. what is field energy and co-energy ? (10)
Unit -4
1. Explain generated voltage in AC and DC machines. (16)*
2. Explain MMF in single coil winding .(8)*
3. Explain MMF in a multiple coil distributed winding (16)*
4. Explain and derive the torque in round rotor machines in terms of flux and flux density.(16)
Unit -5
1. Explain the methods of excitation in DC generators (16)*
2. Explain characteristics of DC generator.(16)*
3. Explain in detail the armature reaction in the DC machines. (16)*
4. Explain the process of commutation and the methods to improve the commutations .(16)*
5. Explain the three point starter in detail with diagram .(8)
6. Explain the methods speed control of DC shunt motor. (8)*
7. Explain the methods speed control of DC series motor.(8)
8. Explain any 2 methods of testing of DC machines .(8)*